The subject matter of the present application is directed to a method for routing messages forwarded according to an asynchronous transfer method with 100% line utilization.
Routing devices that can comprise a plurality of blocks are utilized for matching to the data rates of interfaces. A block may adapt (or shape) the data rate of a virtual path. The data of a plurality of blocks may be supplied to an interface. A standardized interface supports back pressure of traffic. When only one block supplies data to the interface and the data rate set for the block is somewhat higher than the data rate of the interface, a 100% load rate can be achieved for the interface. When the data of a plurality of blocks, i.e. a plurality of virtual paths, are supplied to an interface that supports back pressure of traffic, then a 100% load rate of the line interface is not established.
The subject matter of the present application is based on the problem of providing a method wherein a load rate of 100% can be achieved for an interface to which a data of several blocks are supplied.
The problem is solved by a method for routing message cells forwarded with an asynchronous transfer method with 100% line utilization, wherein message cells intermediately stored in a plurality of blocks are intended for forwarding via an interface; the sum of the message cell rates declared for the blocks is somewhat higher than the message cell rate of the interface; the interface outputs a back pressure signal when its message cell rate is exceeded; a counter is established for every block; the counters are clocked with a clock signal whose cycle corresponds to a message cell cycle; when reaching a counter reading that corresponds to the message cell rate declared for the appertaining block, a counter outputs an operate signal (or flag) for the forwarding of a message cell; given non-presence of a message cell intended for forwarding, every block outputs an empty signal; an active operate signal is only output for a block when no active back pressure signal and no active empty signal are established; a block exhibits a low priority; and a scheduler block scheduler for each message cell cycle allocates an authorization for forwarding of a message cell to exactly one block based on the criterion of the level of priority of the blocks for which an active operate signal is supplied to the scheduler block scheduler at the moment.
The subject matter of the present application avoids the routing of dummy data for a block that in fact receives an authorization for forwarding data according to the data rate declared for it but does not have any data at the moment. The subject matter of the application yields a complete utilization of the line interface with payload data.